This paper describes a procedure that has been designed to measure P(0;0), P(2;0) and P(1;90), the three values that are the basis for the C1-C2 system for measuring road reflection of light. The system was proposed in The Netherlands, and subsequently adopted by the CIE as an alternative to the Qo-kappa system. The function P(x;y) is the luminance factor as commonly defined, but divided by pi = 3.14159..., x is the tangent of the angle of incidence in the plane of observation, and y is the angle in degrees in the plane perpendicular to the plane of observation. The three specific P-values can easily be measured in a laboratory, using samples cut out from the road. The reflection properties of road surfaces were also measured on-site, as part of a project to establish an optimal design and maintenance system for the lighting system in a medium-sized Dutch city and to optimise its public lighting in terms of energy. Five roads with a traffic function were selected for this test. Their classes were assessed, their reflections were measured using a prototype of the C1-C2 system, a lighting installation was designed to allow the recommended luminance levels, and the calculated and observed power levels were compared. The results are given in a table.
Samenvatting